Preheat oven to 400 F (205 C). Grease a shallow 11" x 7" baking pan with butter. Put butter, sugar and corn syrup in a large saucepan; stir continuously over medium heat until melted. Remove from heat. Stir rolled oats into melted mixture. Spread half of mixture in bottom of pan to form a thin layer. Press with the back of a spoon to compact the mixture and smooth the top. In a medium-size bowl, mix apricots, dates and prunes together. Sprinkle evenly over top of packed mixture. Spread remaining mixture on top of fruit; press with spoon again. Bake about 20 minutes or until lightly browned. Cool 5 minutes. Using a knife, mark surface of mixture with lines to use as a guide for cutting. Leave in pan to cool completely. Cut in squares, then lift out with a small spatula. Store in an airtight container in a cool place for up to 1 week.